Interpretive Summary: Pear leaf spot, caused by the fungus Fabraea maculata Atk. (anamorph: Entomosporium mespili (DC.) Sacc.) occurs in most areas of the world where pears are grown. Most major cultivars of the European pear, P. communis L., for which data are available are susceptible. Ratings appearing in the literature are sometimes contradictory and are based upon observations of natural infections in non-randomized orchards plots. This study evaluated resistance/ susceptibility within a diverse collection of Pyrus cultivars and other germplasm in a randomized and replicated nursery plot using quantitative measures of disease incidence and severity. The least susceptible pears were the P. communis cultivars `Beurre Fouqueray' and `Bartlett', the P. pyrifolia cultivars `Imamura Aki', and the P. communis x P. ussuriensis hybrid NJ 477643275. The screening nursery appears to be sufficiently useful to breeders and plant pathologists for identifying the most resistant and the most susceptible cultivars and selections. These resistant pears will be useful in developing new cultivars with resistance to Fabraea leaf spot.

Technical Abstract:
Pear leaf spot, caused by the fungus Fabraea maculata Atk. (anamorph: Entomosporium mespili (DC.) Sacc.) occurs in most areas of the world where pears are grown.
Most major cultivars of the European pear, P. communis L., for which data are available are susceptible. Ratings appearing in the literature are sometimes contradictory. This study evaluated resistance/susceptibility within a diverse collection of Pyrus cultivars and other germplasm in a randomized and replicated nursery plot using quantitative measures of disease incidence and severity. The least susceptible genotypes were the P. communis cultivars `Beurre Fouqueray' and `Bartlett', the P. pyrifolia cultivars `Imamura Aki', and the P. communis x P. ussuriensis hybrid NJ 477643275.